The present invention relates generally to sheet-fed offset printing machines, and more particularly, to quality control consoles for such printing machines.
Sheet-fed offset printing machines often have operating or trimming desks on which a proof sheet can be placed and inspected visually. Such desks generally have a sheet support surface mounted at an angle with respect to the horizontal so that a proof sheet placed on the desk can be assessed by an operator. In the case of larger sheet-fed offset printing machines, such trimming desks generally are located at a control station of the machine in the vicinity of the delivery unit upon which sheets are slacked following printing. A proof sheet removed from the delivery unit can be placed on the desk and assessed. The desk additionally can have operating controls for remote adjustment of various operating items in the printing machine, and in particular, for remotely adjusting and controlling inking zones of the machine. If the proof sheet is deposited on the desk and compared with the intended zonal inking arrangement, for example, the operator can make inking changes in the respective ink metering zones to effect the necessary correcting adjustments.
German patent DE 42 26 842 C1 discloses and apparatus for controlling an offset printing machine with a delivery unit of the machine having an operating panel which can be moved between operating and parked positions. The operating panel includes devices which enable remote control of the printing apparatus, including remote zonal ink control. In the operating position, the operating panel is at a height which corresponds approximately to the top of the delivery stack. If the operating panel is no longer needed, it may be folded down and located downstream of the delivery stack.
A disadvantage of such prior apparatus is that accessibility to the deliver stack is impaired. In particular, in the case of small format sheet-fed offset printing machines in which predominantly small editions are printed, the delivery stack, and therefore the entire delivery unit is not very high, so that the operating panel arranged in the foregoing manner as a proof sheet support cannot be arranged at an ergonomically desirable height for the operator.
German patent EP0 213 439 B1 discloses a sheet-fed offset printing machine with a chain delivery sheet conveyor and a control desk, with the control desk having a support surface for proof sheets directly downstream of the delivery stack in the sheet running direction. By means of an appropriately designed proof sheet removal device, the sheets to be inspected can be placed directly on top of the desk. The desk likewise has controls for remote operating adjustments, and in particular for adjustment of remote inking zones.
The disadvantage in this case is that, as in the aforementioned apparatus, accessibility to the delivery stack is impaired. The deliver stack no longer can be changed from the end of the machine in the direction of sheet transport, and the overall length of the machine is increased.
It is an object of the present invention to provide a sheet-fed printing machine having an easy to use control panel which does not obstruct access to the deliver unit of the printing machine. Another object is to provide a sheet-fed printing machine as characterized above in which the control panel does not increase the overall length of the printing machine.
A further object is to provide an offset printing machine of the above kind in which the control panel has a test sheet support surface that is at a comfortable height for the operator to use.
Still another object is to provide an offset printing machine of the foregoing type in which the control console is relatively simple in construction and lends itself to economical manufacture.
The invention is carried out by a console having a test sheet support surface disposed over the delivery stack at a height at which sheets can be comfortably viewed by an operator of average height. The sheet support surface has a size that even a larger sheet format processed through the machine can be deposited on it.
According to a preferred embodiment of the invention, the sheet support surface of the control console has an inclination with respect to the horizontal, the angle of inclination preferably being between 30 and 45 degrees. In such embodiment of the invention, stops or a stop rail are located adjacent the bottom of the support surface so that a deposited sheet can be aligned on the stop rail.
According to a further preferred embodiment of the invention, adjustable stops are provided on the support surface for supporting a deposit sheet in aligned relation to its zonal metering format. This embodiment preferably is used when control devices are provided along a lower end of the support surface for permitting adjustment in remote inking zones of the printing machine. Hence, after a proof sheet has been delivered onto a delivery stack under the support surface and then deposited on the support surface, an operator can inspect the quality and correct it as necessary through adjustment in the appropriate ink metering zones.
According to still a further preferred embodiment of the invention, the sheet support surface includes a lighting device adapted for providing a glare free and reflection free illumination of sheets deposited on the inclined sheet support surface.
The control console of the present invention allows for simple and comfortable observation of proof sheets even in low stack delivery units in which the delivery stack has a relatively low height. The deposit surface is disposed above the delivery stack and preferably arranged at a height of about one meter above the floor and preferably at an angle of between 30 and 45 degrees with respect to the horizontal. An operator of average height can thereby remove a printed sheet transferred to the underlying delivery stack and easily place it on the deposit or support surface of the control console. By means of an appropriate alignment element or elements, which can be adjusted on the support surface in accordance with the inking format of the sheet, the proof sheet can be aligned in accordance with the ink metering zones of the printing machine. If the support surface includes further operating and indicating elements or controls, in addition to operating elements for the adjustment of the remote inking zones, essentially the entire printing process can be monitored and controlled from the location of the delivery unit.
Moreover, since the support surface for the sample sheets is arranged above the delivery stack, the overall length of the machine is not increased. With the support surface of proof sheets inclined in the foregoing manner, electrical and/or mechanical components of the machine or additional equipment further can be accommodated in the space between the underside of the support surface and the chain sheet transfer conveyor for the delivery unit.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: